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An Sc 310 > Lec 9 - CNS Integrated Fxns > Flashcards

Lec 9 - CNS Integrated Fxns Flashcards

1
Q

define reflexes, what pathways do they use

A

-automatic patterned responses to a stimulus (no conscious intervention)
-use pathways for involuntary responses

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2
Q

what are reflex arcs, what are the 5 components

A

-neural pathways for reflexes
1. sensory receptor
2. afferent neuron
3. integration centre
4. efferent neuron
5. effector organ

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3
Q

describe the pathway of a reflex arc

A

stimulus triggers sensory receptor, afferent neurons carry info to integration centre, this sends info via efferent neurons to effector organs to create a response

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4
Q

what types of muscles and tissues do somatic and autonomic motor neurons ctrl

A

-somatic: skeletal muscle
-autonomic: smooth and cardiac muscle, glands, adipose tissue

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5
Q

are spinal reflexes or cranial reflexes integrated in the brain

A

-cranial, spinal do not require input from brain

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6
Q

what is the diff b/w innate and learned reflexes

A

-innate are genetically determined, we are born w it
-learned are conditioned responses that are learned through experience

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7
Q

how many neurons are in monosynaptic and polysynaptic reflexes

A

-mono: only an afferent and efferent
-poly: have one or more interneurons b/w the afferent and efferent neurons

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8
Q

are somatic and autonomic reflexes mono or polysynaptic

A

-auto: poly (have one afferent and two efferent neurons)
-somatic: both

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9
Q

what is an example of a muscle spindle stretch reflex

A

-knee jerk reflex

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10
Q

what is the only known monosynaptic reflex, describe how it recognizes and sends a signal to the spinal cord

A

-stretch reflex (knee jerk)
-receptor is a muscle spindle that detection the muscle getting longer, tapping the patellar tendon below the kneecap stretches the quad muscle which excites the muscle spindles and sends and AP via afferent neurons to spinal cord

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11
Q

muscle spindles are stretch receptors and are also called ____, what do they detect

A

-proprioceptors
-sense changes in muscle length

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12
Q

what do muscle spindles run parallel to, what are they made of

A

-contractile extrafusal muscle fibres
-made of a connective tissue capsule that encloses a group of intrafusal fibres

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13
Q

which parts of intrafusal muscle fibres are contractile, what nerves supply them

A

-ends
-gamma motor neurons

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14
Q

which parts of the intrafusal muscle fibres are non contractile and why, what is this region stimulated by, what does it do when the muscle is at rest length

A

-central
-lacks myofibrils
-stimulated by stretch
-when muscle is at resting length, central region of muscle spindles is stretched enough to activate sensory neurons

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15
Q

what does it mean for the muscle spindles to be tonically active, where do the sensory neurons synapse, how do they keep the muscle at a tone, what is muscle tone

A

-tonically active: to send a steady stream of APs to the spinal cord
-synapse to alpha motor neurons in the muscle
-keep muscle at a tone by continuously activating motor neurons
-muscle tone is the lvl of tension a muscle maintains at rest

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16
Q

what happens when movement stretches the muscles, what neurons keep the muscle spindles active

A

-stretched muscle causes the spindle fibres to stretch and their sensory fibres fire more rapidly creating a reflex contraction of the muscle to prevent overstretching
-gamma motor neurons

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17
Q

what is a stretch reflex

A

reflex pathway where muscle stretch initiates a contraction response

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18
Q

what are the 4 parts of a voluntary motor task

A
  1. forming an idea to move
  2. put tgt a program of motor commands to carry out movement
  3. execute movement by activating proper muscles at proper time
  4. feedback is constant to ensure the movement is carried out smoothly and successfully
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19
Q

what three lvls of the NS ctrl movement, what type of movement does each ctrl

A
  1. spinal cord (integrates spinal reflexes, has central pattern generators for maintaining spontaneous repetitive activity w/out signal input)
  2. brainstem and cerebellum (posture, hand and eye movement)
  3. cerebral cortex and basal ganglia (voluntary movements)
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20
Q

the thalamus relays and modifies ____ as they pass from the _________ to the ___

A

-signals
-spinal cord, basal ganglia, cerebellum
-cerebral cortex

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21
Q

what three parts of the brain are needed for voluntary movements

A

-cerebral cortex
-cerebellum
-basal ganglia

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22
Q

what are the 3 steps of a voluntary movement

A

-decision making/planning
-initiating movement
-executing movement

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23
Q

what is a lower motor neuron, is it excitatory or inhibitory, how does it contract and relax a muscle cell

A

-one motor neuron to skeletal muscle cell and is located in spinal cord
-excitatory
-to contract: activate lower motor neuron (send AP)
-to relax: do not activate (no AP)

24
Q

what two tracts send input to lower motor neurons

A

-pyramidal tract neurons
-extrapyramidal tract neurons

25
Q

what movement does the pyramidal tract ctrl, are they upper or lower motor neurons, where are they found, what do they do, where do they cross

A

-fine ctrl of distal extremities (arms, hands, fingers)
-upper motor neurons located in primary motor cortex
-direct input to lower motor neurons
-cross to contralateral side in medullary pyramids

26
Q

what are extrapyramidal tracts (EPT), what movement are they involved in, what neurons do they send input to

A

-all motor pathways outside pyramidal tracts
-support voluntary movement of proximal extremities and ctrl movement of trunk, neck, legs to maintain posture
-also involved in regulating involuntary motor fxns
-indirect input to lower motor neurons

27
Q

what extrapyramidal tracts correspond to: superior colliculus, red nucleus, vestibular nucleus, reticular formation

A

-tectospinal tract
-rubrospinal tract
-vestibulospinal tract
-reticulospinal tract

28
Q

what extrapyramidal tracts are involved in involuntary ctrl of posture by the brainstem, where does the brainstem receive info from

A

-reticular formation
-vestibular nuclei
-red nuclei
-info from sensory receptors in skin, muscles, joints, vestib apparatus, as well as eyes and ears

29
Q

in what ways does cerebellum ctrl motor coordination, can the cerebellum initiate muscle contraction, why does it compare actual and planned movements

A

-feedback ctrl of motor fxn
-contributes to muscle tone
-stores programs for remembered motor activities
-coordinates gait and maintains posture
-cannot initiate muscle contraction
-sends discrepancies of actual vs planned movement to cerebral cortex to make corrections

30
Q

define sleep, does it require energy

A

-a reversible and normal suspension of consciousness OR an easily reversible state of inactivity w a lack of interaction w external enviro
-active process that needs energy, homeostatic process

31
Q

what are the reasons for sleep

A

-conserve energy
-avoid predators
-repair body
-process memories
-rest brain
-immune fxn
-clearing waste out of CSF
-growth

32
Q

what happens if animals are deprived of REM sleep

A

-shortened lifepspans, sleep deprivation also impairs performance

33
Q

what does an EEG measure

A

-electrical activity of brain

34
Q

what are the 4 stages of sleep

A

-wake stage
-REM sleep
-slow wave or non-REM
-non REM stages which are N1, N2, N3

35
Q

what kind of waves do awake and REM sleep have, how often does REM sleep occur

A

-awake = alpha
-REM = beta
-90 minutes

36
Q

what types of waves are N1 and N2, and N3

A

-1 and 2: theta
-3: delta waves

37
Q

describe the three stages of non REM, what does the body do during this time

A

-N1: lightest stage of sleep
-N2: deeper sleep
-N3: slow wave/deep sleep, hardest to wake (delta waves are high amplitude and low frequency w long duration)
-animal adjusts body position w/out conscious command from brain

38
Q

what body fxns are increased and decreased during non-REM

A

+ growth hormone secretion
- muscle activity, heart rate, respiration rate, O2 consumption

39
Q

what are the two main brain structures that regulate non REM

A

-thalamus
-cerebral cortex (forebrain)

40
Q

what is REM sleep, what is it regulated by, when does it occur, what happens to the length of stages during the night

A

-more active period of sleep w intense brain activity
-regulated by brainstem
-occurs after N1-3, every 90 minutes
-REM phases get longer through night

41
Q

what is the body doing during REM

A

-increased brain activity
-inhibited voluntary muscles
-rapid eye movement
-dreams !

42
Q

do dreams occur in REM or non-REM

A

REM

43
Q

when does the deepest sleep occur

A

-first 3 hours

44
Q

what is the amplitude and frequency of waves in REM, which muscles move vs not, what happens to homeostatic fxns

A

-low amplitude high frequency (similar to awake)
-brain inhibits motor neurons to skeletal muscles which paralyzes them
-only muscle movement occurs in eyes and breathing
-homeostatic fxns are depressed and body temp falls towards the temp of the surroundings

45
Q

describe the sleep cycle through non-REM and REM

A

-animal moves from wakefulness to stages N1 and 2, then into deep sleep N3
-cycles b/w deep sleep and REM w N1 and N2 occurring b/w
-end of sleep period is mostly N1 and REM until awake

46
Q

who do mammals share non-REM and REM sleep w, what animals sleep standing up, which animals do not become unconscious, do insects fall asleep, what animals sleep uni-hemispherically

A

-birds
-horses, cows, elephant, giraffe
-fish and amphibians
-no
-dolphins, whales, seals, and migratory birds

47
Q

what does the SCN do

A

-suprachiasmatic nucleus ctrls circadian rhythm by producing melatonin
-melatonin triggers sleep and lvls fall in the morning

48
Q

what is the ARAS

A

-ascending reticular activating system
-awakens the cortex
-part of the reticular formation
-has projections to thalamus, hypothalamus, and forebrain

49
Q

what sleep stage does forebrain induce

A

non-REM

50
Q

are norepinephrine, serotonin, and orexin high during wakefulness or sleep

A

-wake

51
Q

are acetylcholine and dopamine high during wakefulness, REM, or non-REM

A

-high in wake and REM
-low in non-REM

52
Q

describe the process of falling asleep

A
  1. nerves from eye send signals to SCN that light lvl is decreasing
  2. SCN stimulates ventrolateral preoptic nucleus
  3. ventrolateral preoptic nucleus decreases activity of reticular formatoin
  4. decreased activity disconnects the thalamus from cerebral cortex to decrease lvl of consciousness
53
Q

what is orexin, what does it do

A

-NT released by hypothalamic neurons
-increases before wakening and maintains state of awake
-stimulates reticular formation
-activated formation stimulates thalamus which sends external sensory info to cerebral cortex

54
Q

what are the 3 groups of neurons that are inactive at sleep, which two trigger arousal

A
  1. cholinergic neurons
  2. noradrenergic neurons
  3. serotoninergic neurons
    -1 and 2 trigger arousal
55
Q

what does sleep deprivation cause

A

-temp imbalance, weight loss, weakened immunity, decrease in cognitive abilities, hallucinations, death

56
Q

how is sleep affected during infection, what microbes mimic the sleep effect, what increases non-REM duration, do sleep disorders affect immune competence

A

-sleep increases during infection, N3 increases and REM decreases
-LPS and muramyl peptides
-increase in lvls of TNF and IL1
-yes

An Sc 310 (7 decks)

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